In a large bowl cream together butter and sugars until light and fluffy.
Add the eggs, vanilla and milk and beat until smooth and well mixed.
In a separate bowl, mix flour, hot chocolate mix, salt, baking soda, and baking powder.
Gradually beat the dry ingredients into the butter mixture until blended.
Stir in chocolate chips
Cover and refrigerate for 30 minutes.
Preheat oven to 350°F
Drop dough by tablespoonfuls, about 2 inches apart, onto baking sheets lined with parchment paper.
Top each cookie with 3-4 marshmallows, pressing marshmallows into dough.
Bake for 9-10 minutes.
Remove to a cooling rack to cool for a few minutes before serving.
Store in an airtight container.